Wavelength division multiplexing transmission system

A wavelength division multiplexing transmission system for transmitting wavelength division multiplexing signals comprising:

• at least one of a demultiplexing module unit and a multiplexing module unit, said demultiplexing module unit further comprises:
• a first interleave filter unit demultiplexing said wavelength division multiplexing signal into a signal light of a first channel group, that is one of an even channel group and an odd channel group and a signal light of a second channel group, that is the other thereof, and outputting the demultiplexed signal lights,
• wherein a first signal light of which the signal bandwidth is relatively large can be allocated to each channel of said first channel group, and a second signal light of which the signal bandwidth is relatively small is allocated to each channel of said second channel group;
• a first demultiplexing unit demultiplexing the signal light of said first channel group from said first interleave filter unit and outputting these signal lights, and
• said multiplexing module unit further comprises:
• a first multiplexing unit multiplexing a plurality of said first signal lights or said second signal lights that are input, into a signal light of said first channel group and outputting the signal, and
• a second interleave filter unit inputting a signal light of said first channel group from said first multiplexing unit, and a signal light where a plurality of said second signal lights are disposed in said second channel group, multiplexing these two input signal lights to generate said wavelength division multiplexed signal, and outputting the multiplexed signal,
• wherein the first interleave filter unit includes a first port for outputting a signal light of the first channel group and a second port for outputting a signal light of the second channel group, and
• the first and second ports are set such that the bandwidth of a transmission band where light transmits and the bandwidth of a non-transmission band where light does not transmit are different, the transmission band of the first port substantially matches with the signal band of the first signal light and the transmission band of the second port substantially matches with the signal band of the second signal light, and
• wherein said first signal light is disposed in each channel constituting said first channel group, and
• said first demultiplexing unit further comprises:
• a first interleaver demultiplexing the signal lights of said first channel group from said first port of said first interleave filter unit into a signal light of an even channel group constituting said first channel group and a signal light of an odd channel group constituting said first channel group and outputting the signal lights;
• a second interleaver demultiplexing the signal light of said even channel group from said first interleaver into a signal light of an even channel group and a signal light of an odd channel group and outputting the signal lights;
• a third interleaver demultiplexing the signal light of said odd channel group from said first interleaver into a signal light of an even channel group and a signal light of an odd channel group and outputting the signal lights;
• and
• four demultiplexers demultiplexing the signal lights of an even channel group and an odd channel group from said second interleaver and the signal lights of an even channel group and an odd channel group from said third interleaver into signal lights with each wavelength, respectively.